1. Field of the Invention
This Invention relates to a cross-arm mounting bracket for poles The invention is applicable to the mounting of cross-arms on electricity or telephone poles or the like.
2. PRIOR ART
Each year there are many disruptions to electricity supply due to the failure of the cross-arms on electricity poles. The cross-arms are subject to great extremes of temperature (e.g. from -30.degree. C. to +60.degree. C.); extremely high solar radiation; rainfall; high winds; humidity changes (from 10-100% which causes the timber to swell and shrink generating internal stresses); and industrial pollution and salt spray settling; on the arms, which attacks the timber.
To these atmospheric conditions must be added the weaknesses induced in the cross-arms by the holes drilled therein to receive the king bolts mounting the cross-arms to the posts; the holes for the diagonal braces; and the holes for the insulators. Not only do these holes reduce the effective dimensions of the cross-arms but they are also liable to rot and decay, which increases their size and reduces the cross-arm strength. Movement of the insulator pins in their holes, especially as the timber shrinks, further increases the problem.